Background: Many prescription medicines have been converted to over- the-counter (OTC) status, allowing people to self diagnose and medicate without physician supervision. Little is known about the impact of this switch in self-care. Pyridium, an analgesic traditionally prescribed to treat urinary tract infection pain, was recently converted from prescription to OTC. This is the first U.S. study on the use of a post- conversion drug by the lay public. Specific Aims: 1) To describe the characteristics of the population that uses OTC pyridium. 2) To determine the factors associated with knowledge, appropriateness of use, and substitution of OTC pyridium for physician visits. Methods: A cross- sectional survey of purchasers of OTC pyridium in a stratified random cluster sample of 30 pharmacies in Los Angeles County. The survey instrument is a self-administered, anonymous, 25-items questionnaire filled out by customers at the time of purchase. Main Outcome Measures: Knowledge, appropriateness of use, and intentional substitution of OTC pyridium for physician visits. Significance: This study will increase physician's awareness of self-care practices among patients and determine the need for intervention to assure safe OTC pyridium use and proper medical treatment of urinary symptoms. We hope to provide feedback on the prescription-to-OTC debate. We will also test a novel community pharmacy based method and design for data collection.